/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.format.datetime.joda;

import java.util.TimeZone;

import org.joda.time.Chronology;
import org.joda.time.DateTimeZone;
import org.joda.time.format.DateTimeFormatter;

import org.springframework.context.i18n.LocaleContext;
import org.springframework.context.i18n.LocaleContextHolder;
import org.springframework.context.i18n.TimeZoneAwareLocaleContext;
import org.springframework.lang.Nullable;

/**
 * A context that holds user-specific Joda-Time settings such as the user's
 * Chronology (calendar system) and time zone.
 *
 * <p>A {@code null} property value indicate the user has not specified a setting.
 *
 * @author Keith Donald
 * @see JodaTimeContextHolder
 * @since 3.0
 */
public class JodaTimeContext {

    @Nullable
    private Chronology chronology;

    @Nullable
    private DateTimeZone timeZone;

    /**
     * Return the user's chronology (calendar system), if any.
     */
    @Nullable
    public Chronology getChronology() {
        return this.chronology;
    }

    /**
     * Set the user's chronology (calendar system).
     */
    public void setChronology(@Nullable Chronology chronology) {
        this.chronology = chronology;
    }

    /**
     * Return the user's time zone, if any.
     */
    @Nullable
    public DateTimeZone getTimeZone() {
        return this.timeZone;
    }

    /**
     * Set the user's time zone.
     * <p>Alternatively, set a {@link TimeZoneAwareLocaleContext} on
     * {@link LocaleContextHolder}. This context class will fall back to
     * checking the locale context if no setting has been provided here.
     *
     * @see org.springframework.context.i18n.LocaleContextHolder#getTimeZone()
     * @see org.springframework.context.i18n.LocaleContextHolder#setLocaleContext
     */
    public void setTimeZone(@Nullable DateTimeZone timeZone) {
        this.timeZone = timeZone;
    }

    /**
     * Get the DateTimeFormatter with the this context's settings
     * applied to the base {@code formatter}.
     *
     * @param formatter the base formatter that establishes default
     * formatting rules, generally context-independent
     * @return the contextual DateTimeFormatter
     */
    public DateTimeFormatter getFormatter(DateTimeFormatter formatter) {
        if (this.chronology != null) {
            formatter = formatter.withChronology(this.chronology);
        }
        if (this.timeZone != null) {
            formatter = formatter.withZone(this.timeZone);
        } else {
            LocaleContext localeContext = LocaleContextHolder.getLocaleContext();
            if (localeContext instanceof TimeZoneAwareLocaleContext) {
                TimeZone timeZone = ((TimeZoneAwareLocaleContext) localeContext).getTimeZone();
                if (timeZone != null) {
                    formatter = formatter.withZone(DateTimeZone.forTimeZone(timeZone));
                }
            }
        }
        return formatter;
    }

}
